The present invention relates to a method and system for automatically controlling, as a group unit, a plurality of vehicles running on a road.
The moving target method (hereinafter referred to as an MT method) is conventionally known as a method for automatically controlling running vehicles on a road.
A system using such an MT method comprises, as shown in FIG. 1, a group of position information equipment 73 for detecting the position and speed of running vehicles, a running control computer 75 for performing the management, control, etc., of the running vehicles on the basis of information on the position detected by the position information equipment 73, and a communication equipment 74 for conducting communication by providing information from the computer 75 to the running vehicle, transmitting a control instruction, and obtaining information from the running vehicle.
The MT method is a control method for, as shown in FIG. 2, setting an imaginary running path 800 on the running control computer 75 equivalent to an actual road (real road), setting a point (moving target hereinafter referred to as an MT) ideally running at a predetermined interval and speed on the imaginary running path 800, or at a vehicle-to-vehicle distance and running speed matching to the meteorological condition such as the falling of snow or frozen surface of a road, and enabling a real vehicle to run in a way to follow the MT. Since the conventional MT method maintains predetermined intervals between moving targets MT on the imaginary running path 800, regularly spaced intervals of moving targets MT are generated on the imaginary running path regardless of whether or not an actual vehicle 100 has entered the real road 76. Therefore, as shown in FIG. 2, the moving targets created in predetermined intervals or at a set vehicle-to-vehicle running distance, consist of two types of moving target, an MT (null MT) 720 not allocated to the running vehicle 100 and MT (allocated MT) 721 allocated to the running vehicle.
As in an example of FIG. 1, an MT (main road MT) 72 is generated on a main road 76 at a predetermined interval and speed and the MT72 is allocated to a vehicle 100 entering a vehicle control section 78. An MT72 (corres. to the MT720 in FIG. 2) not allocated to the vehicle is moved as a null MT72 on the main road 76. As illustrated in the accompanying drawings, null MTs are represented by hollow, circular symbols (i.e., 720, 72) and allocated MTs (i.e., 721, 711, matched with a vehicle) are represented by circles marked with an "X."
A joining MT71 corresponding to the MT72 on the main road 76 is generated on a branch road 77. When the MT71 is allocated to a respective vehicle (joining vehicle 101) entering from the branch road 77, the joining MT711 allocated to the joining vehicle is generated. Further, the null MT72 on the main road 76 corresponds to the joining MT711 allocated to the joining vehicle and is handled as the MT72 on the main road. As best seen in FIG. 2, the joining MT711 allocated to the joining vehicle is set in synchronism with the MT72 on the main road, so that vehicle joining is achieved at a joining point when the joining vehicle 101 synchronizes and becomes controlled by the MT72 on the main road. As best seen in FIG. 1, it is to be noted that the MT71, being not allocated to the vehicle, moves as the null MT71 (corres. to the MT720 in FIG. 2) on the branch road 77.
A second type of method for controlling running vehicles is a vehicle-to-vehicle control method. The vehicle-to-vehicle control method comprises setting a vehicle-to-vehicle detection sensor such as a radar for detecting a distance between individual vehicles and running a given vehicle in a way to keep a predetermined distance relative to a preceding vehicle on the basis of the vehicle-to-vehicle distance detected by the sensor. It is possible to control a plurality of vehicles as a group by combining a vehicle-to-vehicle communication with such vehicle-to-vehicle control.
In the conventional technique using the MT method, however, it is necessary to apply the MT to each vehicle. The interval between the MTs is generally set somewhat greater among various kinds of vehicles so as to provide ample safety even if there is a difference in vehicle length and in braking capability. At vehicle joining, there was some restriction in number of running vehicles per given interval length and hence some restriction in high density/high effective vehicle joining control.
Under the vehicle-to-vehicle control it is possible to increase the number of running vehicles per given section length in comparison with the MT method. For the application of the conventional MT method to the vehicle-to-vehicle control, however, it is necessary to constantly follow the MT so as to be matched to a corresponding vehicle under the vehicle-to-vehicle control. For this reason, the load of a computer necessary to calculate the position, speed, etc., of the MT cannot be ignored. Further, there was also the problem of how effectively the MT of a vehicle running on the main road should be controlled.
It is accordingly the object of the present invention to provide a method and system for controlling a running vehicle group, which enable a running vehicle from a branch road to be joined onto the main road in high density and a high efficient way.